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AD-A243 054 EA1NPG __[_____* m~ 1 - WWI of W '"meMu so"iJR 4 U 15I1WWM a no ofa
1AG WM ofe 1600 now . 41OR O 3.3 RIS PtMO i ATES covINmetober 1991 Final Report 1 Dec 87 to 30 Nov 90
AM S. PUMoiO NumaENs
New Experimental Challenges in Elemental Fluorine 61102F 2303/B2Chemistry; An Emerging Technology
Richard J. Lagow
7. PIBJAQU NSAWIAT1ONAOAE(S) AN'D A0ONSS(U) L 3 PEMOSMMN ORANIAT"11O
University of: TxasDepartment of Chemistry ~''AFOSR.TR .) 6 (9 26Austin, TX 78712
L. WPONSWUAIIMOMOJJS AGENCY NAM(S) AND A00S13(13) IL. SPOWSOGJ44MUMOW
AF GR/NCRolling AFB, DC 20332-6448 AFOSR-88-008 4
IJ&. OSSIUWTH)MIAVAILAINII STATIMENT M2h OISIRUTO cmG
Approved for public release; distribution is unlimited
A controlled fluorination method using elemental fluorine has been 'used tosynthesize a large variety of new compounds from hydrogen-containingprecursors including perfluoroethers, perfluoropolyethers, perfluoro crownethers, and perfluorocryptands. Polyesters were converted to polyethers usinga combination of direct fluorination of the carbon hydrogen bonds andfluorination by SF 4, of the carbonyl groups. A process was developed forpartial fluorination of gas separation membranes. The selectivity of themembranes for size separation was increased significantly up to 103
91-16545
91 112(j 044 MOO___m19 SWCLASMTN I SCOT ASSIAi N lo U.W L" "O UWIATIO OP A&STPACT
co Avon CO TWS PAGE O AmWACUNCLASSIFIED .UNCLASSIFIED UNCLASSIFIED SAR
:2 JUL 1991
COMPLETED PROJECT SUMMARY
TITLE: New Experimental Challenges in Elemental Fluorine Chemistry; An Ac- :-a rEmerging Technology T, 4 iepi
SliC T ct
PRINCIPAL INVESTIGATOR: Richard J. Lagow ; .dDepartment of ChemistryThe University of Texas at AustinAustin, TX 78712-1167 -,... .
INCLUSIVE DATES: 1 December 1987 - 30 November 1990
CONTRACT/GRANT NUMBER: AFOSR-88-0084 A 1-Di~t Ka
SENIOR RESEARCH Ronald AbbottPERSONNEL: Michael Brezinski W
Miguel Guerra....
JUNIOR RESEARCH Scott Battle Michael HovsepianPERSONNEL: Wayne Clark Joel Kampa
James DeYoung Tzuhn-Yuan LinD. Wayne Dyer Wen-Huey LinBrian Eastland Todd Mlsna
PUBLICATIONS:*
"Synthesis of Unusual Perfluorocarbon Ethers and Amines Containing BulkyFluorocarbon Groups; New Biomedical Materials", H.N. Huang, D.F. Persico,
L.C. Clark, Jr. and R.J. Lagow, J. Org. Chem., 53, 78 (1988).
"Synthesis of Perfluoro Crown Ethers: A New Class of Cyclic Fluorocarbons",W.H. Lin, W.I. Bailey, Jr. and R.J. Lagow, Pure Appl. Chem., 60, 473(1988).
"The Preparation of New Perfluoro Ether Fluids Exhibiting Excellent ThermalOxidative Stabilities", W.R. Jones, Jr., T.R. Bierschenk, T.J. Juhlke, H.Kawa and R.J. Lagow, Ind. Eng. Chem. Res., 27, 1497 (1988).
"Synthesis of the First Perfluoro Tetraalkyl Orthocarbonates", W.H. Lin,W.D. Clark and R.J. Lagow, J. Org. Chem., 54, 1990 (1989).
"Synthesis of Bis(trifluoromethyl)xenon", L.J. Turbini, R.E. Aikman, M.M.Brezinski and R.J. Lagow, J. Fluorine Chem., 45, 12 (1989).
"Synthesis of Tetrakis(trifluoromethyl)lead", T.J. Juhlke, J.I. Glanz andR.J. Lagow, Inorg. Chem., 28, 980 (1989).
A.. . : .
"The Synthesis of Perfluorodicyclohexyl-18-crown-6 Ether", T.Y. Lin andR.J. Lagow, J. Chem. Soc., Chem. Commun., 12 (1991).
"Synthesis of Functional Perfluorinated Resins, Branched PerfluorinatedEthers and Perfluoroalkanoyl Fluorides", H.N. Huang and R.J. Lagow, J.Chem. Soc., Perkin Trans. 1, 871 (1991).
"XPS Characterization of Surface Fluorinated Poly(4-methyl-l-pentene)",D.R. Paul, J.M. Mohr, Y. Taru, T.E. Mlsna and R.J. Lagow, J. Appl. Polym.Sci., 42, 2509 (1991).
"A New Synthetic Procedure for the Preparation and Manufacture ofPerfluoropolyethers", T.R. Bierschenk, T.J. Juhlke, H. Kawa and R.J. Lagow,Synthetic Fluorine Chemistry, G.A. Olah, R.D. Chambers and G.K.S. Prakash,Eds., Wiley Interscience, in press.
"Selective Formation of Molecular Oxygen/Perfluoro Crown Ether andPerfluoro Cryptand Adduct Ions (Inclusion Complexes?) in the Gas Phase", J.Brodbelt, S.D. Maleknia, T.Y. Lin and R.J. Lagow, J. Am. Chem. Soc., inpress.
"The Synthesis of Perfluorotrialkyl Orthoformates by Direct Fluorination",T.E. Mlsna, W.H. Lin, M.M. Hovsepian and R.J. Lagow, Eur. J. Solid Stateand Inorg. Chem., in press.
*Some of this work has been completed and published after the termination
of this project on November 30, 1990.
ABSTRACTS OF OBJECTIVES AND ACCOMPLISHMENTS:
At a time when direct fluorination has been successfully scaled up byindustrial concerns (3M and others) in conjunction with a small companycomposed of alumni from this AFOSR research program, our group continues tomake novel contributions to the literature. During this three year period,we prepared the first perfluorocryptand (J. Org. Chem. 1990, 55, 5933).This perfluorocryptand [222] structure:
/CF 2 \CF 2 -CoF2 CF?
cF2 '0 \0 CF2/I CF2 -CF2 o CF2 -CF 2 CF2 -CF2 \
0 0 N
C2'CF2 110CF2 -CF2 ' CF2
along with the perfluoro crown ethers (Pure Appl. Chem. 1988, 60, 473) havebeen ongoing projects in this laboratory. In a collaboration between ourresearch group and the research group of Professor Jennifer Brodbelt we
"A New Trifluorosilyl Exchange Reagent: Reactions of Cd(SiF ) *glyme withDibromo Metal Phosphine Complexes of Platinum, Palladium, ana Nickel YieldTrifluorosilyl Substituted Dialkyl Compounds", M.A. Guerra and R.J. Lagow,J. Chem. Soc., Chem. Commun., 65 (1990).
"A Synthesis for SF, Substituted Fluorocarbon Polymers", H. Kawa, S.N.Partovi, B.J. Ziegler and R.J. Lagow, J. Polym. Sci., Polym. Lett. Ed., 28,297 (1990).
"Synthesis of Tris(trifluoromethyl)gallium and Its Adducts", M.A. Guerra,D.W. Dyer, S.K. Mehrotra and R.J. Lagow, J. Organomet. Chem., 390, C73(1990).
"The Synthesis of Perfluoro Highly Branched Heterocyclic Fluorine Compoundsby Direct Fluorination", W.H. Lin and R.J. Lagow, J. Fluorine Chem., 50, 15(1990).
"A New General Method for Preparation of Pentafluorosulfur-SubstitutedFluorocarbons: The Synthesis of Perfluoroneopentyl Sulfur PentafluorideUsing Elemental Fluorine as a Reagent", H.N. Huang and R.J. Lagow,Chemistry of Materials, 2, 477 (1990).
"The Synthesis of the First Perfluorocryptand", W.D. Clark, T.Y. Lin, S.D.Maleknia and R.J. Lagow, J. Org. Chem., 55, 5933 (1990).
"The Synthesis of Highly Fluorinated Alkylcyclohexanes for Use as OxygenCarriers; and the 19F and 13C NMR Spectra of Alkylcyclohexanes", W.H. Linand R.J. Lagow, J. Fluorine Chem., 50, 345 (1990).
"A Facile Synthesis for Functional Perfluoropolyether Oligomers, Diacids,Diesters and Surfactants", D.F. Persico and R.J. Lagow, J. Polym. Sci.,Polym. Chem. Ed., 29, 233 (1991).
"Novel Synthesis of Unusual Classes of Fluorocarbon Organosulfur CompoundsUsing Elemental Fluorine as a Reagent", H.N. Huang, H.W. Roesky and R.J.Lagow, Inorg. Chem., 30, 789 (1991).
"The Direct Fluorination of Acetone", W.D. Clark and R.J. Lagow, J.Fluorine Chem., 52, 37 (1991).
"Surface Fluorination of Composite Membranes Part I: TransportProperties", D.R. Paul, J.M. Mohr, T.E. Mlsna and R.J. Lagow, J. MembraneScience, 55, 131 (1991).
"Surface Fluorination of Composite Membranes Part II: Characterization ofthe Fluorinated Layer", D.R. Paul, J.M. Mohr, Y. Taru, T.E. Mlsna and R.J.Lagow, J. Membrane Science, 55, 149 (1991).
have recently shown that both perfluorocryptand and perfluoro crown etherstenaciously bind 02 and F (J. Am. Chem. Soc. 1991, in press). We Kiv',also generated several new classes of perfluoro crown ethers (J. Chell.Soc., Chem. Commun. 1991, 12). In addition, we have prepared many newspherical perfluorocarbon fluids based on pentaerythritol species as wellas other types of spherical perfluorocarbon ethers. We have continued ourwork with Professor Leland Clark on strategically designed perfluorocarbonblood substitutes and established a general route to perfluorocarbondiacids and precursors for surfactants (J. Polym. Sci., Polym. Chem. Ed.1991, 29, 233). Another contribution from our group has been the synthesisof some of the first sulfur pentafluoride substituted fluorocarbon polymers(J. Polym. Sci., Polym. Lett. Ed. 1990, 28, 297). Lower molecular weightversions have potential as high density fluids while solid samples andelastomers have potential new dielectric materials. We have also beenworking on new '9F NMR magnetic resonance imaging agents. One of our bestcandidates is the perfluoro 15-crown-5 (J. Chem. Soc., Chem. Commun. 1985,1350; U.S. Patent 4,570,005, 1986; U.S. Patent 4,838,274, 1989). Work hasalso continued on perfluoropolyether fluids. While our off-campus grouphas used the University of Texas technology in conjunction with Air ForceMaterials Laboratory at Wright-Patterson Air Force Base in developing someof the best and most stable nonflammable perfluorocarbon aircraft hydraulicfluid candidates available.
AFOSR Program Managers: Dr. Anthony Matuszko and Dr. Frederick Hedberg
Final Technical Report
to
AIR FORCE OFFICE OF SCIENTIFIC RESEARCH
Boiling Air Force Base, DC 20332
NEW EXPERIMENTAL CHALLENGES IN ELEMENTAL FLUORINE CHEMISTRY;
AN EMERGING TECHNOLOGY
Grant Number AFOSR-88-0084
December 1, 1987 - November 30, 1990
Presented by
Professor Richard J. Lagow
Department of Chemistry
The University of Texas at Austin
Austin, Texas 78712
(512) 471-1032
fl!~ ,,
INTRODUCTION
This is a very exciting time for the chemistry of direct fluorination.
For well over a decade our research group, funded by the Air Force Office of
Scientific Research, has synthesized novel and unusual organofluorine
compounds, many of which could not be prepared using other synthetic methods.
Now this area of chemistry has come of age and one consequence is that there
will be a much shorter lead time, perhaps significantly less than two years,
elapse between the discovery of a potentially new or useful material in the
laboratory and its availability on a commercial scale.
Just this July, 3M Company puts on line a new commercial production
facility using our direct fluorination technology. A public announcement has
been issued concerning 3M's licensing (which occurred secretly four years ago)
of our perfluoroether and perfluoropolyether technology. That technology had
its origin with our AFOSR funded projects. By the fall, the first round of
commercial products will hit the market. Both Exfluor Research Corporation,
an Austin corporation comprised primarily of a small group of former students
from the Lagow laboratory, and 3M have now the capability of making many
gallons per hour of interesting new fluorocarbons using elemental fluorine.
The 3M technology package consisted of numerous patents produced by our group
at the University of Texas along with a number of patents licensed from
Exfluor Research Corporation.
Thus the work done in our laboratory has even greater impact since work
done in the University laboratory (still on an eight to ten gram scale) can be
converted in a relatively short period of time to very useful quantities of
materials in any number of fields such as biomedical research, functional
fluids and lubricants, surfactants and starting materials for new polymers and
polymer systems.
2
Interestingly perfluoropolyether chemistry, one of the areas given our
most attention in our academic laboratory over the last ten years and an area
directly tied to the sponsorship of AFOSR, will constitute the lion's share of
the first several waves of products to hit the market. Elemental fluorine
perfluoroethers and the perfluoropolyether synthetic method came directly out
of our AFOSR program with the first results reported in 1978.1-3
Thus our fluorocarbon program with AFOSR will most certainly develop as
an outstanding example of funding basic research to achieve major impact on
both the industrial and military sectors in the United States. In general,
the Air Force Office of Scientific Research has been our sole support in
exploring this area of chemistry and is certainly the only long term support
for this elemental fluorine research program (several other agencies have
picked specific narrow areas to support for lesser periods of time).
There are important new synthetic techniques emerging from our academic
laboratory presently. In the next three years much more sophisticated work on
more complex, higher molecular weight compounds will be possible. For
example, Tzuhn-Yuan Lin, a very excellent new graduate student in our program,
has been able to synthesize recently molecules such as the fluorocarbon
analogue of the dibenzo crown ethers.
dibenzo 1 8J-own6
Tzuhn-Yuan Lin has prepared and we have recently submitted for publication in
Chemical Communications two interesting isomers of perfluorodicyclohexyl-18-
crown-6 ether, the cis-syn-cis and cis-anti-cis isomers.4 Their structures
have also been established by X-ray crystallography.
3
cC22 C24
View (ORTEP) of cis-syn-cis (1) showing the atom numbering
scheme. Distances (A ) between adjacent oxygen atoms are as follows: 013-
02 C 2.662, 02 0 0a 2.713, O23-26 2.665, C2-7 2.667, O-Ob 2.707,
Olo-Ols 2.667. Distances (A ) between oxygen atoms to center of the
molecule ae follows: 0T 2.536, O~o 2.129, Ou3 3.177, 020 2.543, 023 2.141,
026 3.181.
View (ORTEP) of cs-anti-cis (2) showing the atom numbering
scheme. Distances (A) between adjacent oxygen atoms are as follows: O0,-
O0 2.727, 013-07 2.702, O7-Oi0 3.525. Distances (A) between oxygen
atoms to center of the molecule are follows: 0 3.156, 00 2.403, 023 3.332.
4
This is just an example of how well we can do with our direct fluorination technology
at the present time. We expect that high molecular weight limitations will be
nonexistent as we progress during the next three year period.
It is very significant that one of the new concepts enabling high volume
production and scale-up of direct fluorination came from an experiment in our
laboratory which was done several years ago, namely the synthesis of the
perfluorinated analogue of Geoff Wilkinson's compound hexamethyltungsten by direct
fluorination. It was very surprising that Robert Aikman, toward the end of his Ph.D.
thesis, was able to convert hexamethyltungsten (containing a 20-30 kcal
tungsten-carbon bond) to the fluorocarbon analogue in at least fifty percent yield.
W(CH 3)6 rZ/N t W(CF 3 ), -5O% yield€lrcl 3
CFCS3
W(CF 3 ) PEt 3
F19 nm . 68.5 ppm (CFCI 3 )
.L J('8 3W- F) •110 H
We have previously based our successful fluorinations on the philosophical
approach developed by Lagow and Margrave and explained in Progress in Inorganic
Chemistry 5 where direct fluorination was slowed down and carefully controlled by the
supply of elemental fluorine as well as moderated with temperature control and other
techniques like the Lagow cryogenic zone reactor.5
Thermodynamic Data for Steps in Fluorination of CH. a
Step Reaction All ,OK AHN..*K AG,,K AG,9..Kkcal mole -' kcal mole-1 kcal mole -'kcal mole'
Initiation la F, - 2F, + 37.7 + 38.5 + 29.55 20.9lb F, +RH-R.+HF F- +3.9 +5.1 -5.84 -18.904
Propaption 2a RH+F--R'+ HF -33.8 -33.4 -36.215 -37.512b R" +F, - RF+F- -69.1 -69.5 -68.1 -64.15
Termination 3a R- + F. - RF -106.8 -108.0 -97.5 -85.0913b R- + R - R - R -83.8 -83.06 -70.3 -57.5
Overall reaction R - H + F, - RF * HI" - 102.9 -102.9 -103.4 -103.9
a Based on JANAF Table data for CH 4 .
5
1.0 --- - - - - - - - - - - - - - - -
00 04 a8
TW* in hrs
Fluorine dilution scheme direct fluonration.
It was amazing that direct fluorination was capable in CFCl3 at temperatures such as
-90 °C was capable of preserving 20-30 kcal bonds when the overall reaction to
replace even one hydrogen is over 100 kcal.
Most of our newer approaches, and there are more than one, are based on a new
philosophy. Direct fluorination has many advantages for commercial and large-scale
production as well as making large high molecular weight and sophisticated molecules
for both kinetic and thermodynamic reasons. Although it was always expected, it has
been established over the last ten years that reaction of elemental fluorine with
hydrocarbons are perhaps the, or one of the, fastest reactions in all of chemical
science.
The activatien energies for molecular fluorine to abstract a proton from an
alkene has been reported in different studies to range from a real activation energy
of zero to as high as 1 cal/mole (not 1 kcal/mole). These studies were reported by
such researchers as Dick Bernstein of UCLA, Doug McDonald of the University of
Illinois, and Dick Zare of Stanford. The exact number obtained for the activation
energy depends on the method of measurement. A number of these results have come
from crossed-beam reaction studies.
It has been known for some time, and is discussed in our Progress in Inorganic
Chemistry article, 5 that the full substitution and replacement of protons on
6
hydrocarbons is among the most exothermic reactions known. Thus if we neglect one
small problem, namely control of the reactions of elemental fluorine, we are dealing
with a reaction chemistry which has unique advantages for chemical processing. There
is, in principle, no limit to how fast these reactions with activation energies below
I cal/mole can take place on an industrial scale. We also have a reaction whose
thermodynamics are so favorable (exothermic) that the reaction proceeds very far to
the right and in fact can be quantitative in favorable instances. In most industrial
chemistry processes, most of the primary obstacles are equilibrium problems.
Successful chemistry often depends on catalysis or other methods for shifting
equilibrium concentrations in the desired direction. Direct fluorination chemistry
has essentially no equilibrium problem at all. Therefore industrial or academic
scale reactions can be conducted very rapidly and efficiently, and in much higher
yields than we ever thought possible.
With these advantages, the reaction chemistry we are dealing with has only one
major problem. There is a need for a technique or system, perhaps involving a rapid
heat sink, for removing energy from the reaction very rapidly. Essentially what we
are describing is an energy density problem. The vibrational relaxation must be
rapid and efficient enough to keep the average energy density down after excited
hydrocarbon free radicals are generated by reaction with fluorine molecules or
fluorine atoms. The goal is that only the early (first through third) vibrational
excited states of the molecules be populated and that these may be relaxed without
ever entering the danger zone, namely the higher excited states close to the
dissociation energy for a carbon-carbon bond or a carbon-fluorine bond.
It is known that cooled solvents are among the most efficient media for
vibrational relaxation. One important technique involved the prototype low
temperature solvent reactor developed in our laboratory for the W(CF 3 )6 synthesis.
7
SOLUTOPSAMPLING OJTLET Fzft @Kr
l TWRE OUPL.E WELL
F /HLOCAROM WAX
STRIP SLVEREDDEWAR
COOLING BATHLIQUID LErVE£L
SOLUTION ,,, ,LIQUID LEVE q OLNG COKt.S
ti&GNE[TICSTIlRR
Thus we predict that the chemical engineer of the future, after the full scale
production capabilities of direct fluorination are well known and established, will
say, "What I would really like is another reaction like direct fluorination to
scale-up". He may have to search very far for one that is again so efficient. The
solvent reactor is just one way to efficiently vibrationally relax the hydrocarbon
species and we have developed techniques that control the reaction by both limiting
the fluorine supply or by limiting the supply of hydrocarbon or other classes of
reactants.
Professor Lagow and his former students have refined these processing techniques
at Exfluor and since the patents are now issuing, we are reintroducing these into our
academic laboratory. The result will be an increased capability of synthesiLing
exotic new species at the University of Texas plus much higher yields. The scale in
the University laboratory will still be at the ten to fifteen gram level (up from one
to two grams several years ago) for our mission in the University laboratory is to
synthesize new and interesting molecules, not to do scaled-up chemistry.
To give an example of the impact, Dr. Hsu-Nan Huang, a former member of our
laboratory now at Du Pont, had a working relationship with Leland Clark where he
8
supplied a gram or 'o of a new compound each month in exchange for physiological
property data and oxygen solubility work. Thus we have a storehouse of knowledge on
very interesting things and now that gallon scale can be provided off-campus, the
academic work will have much higher impact in the oxygen carrier area. There is a
whole lot of difference in the real world when there is one gram than when there is
the potential for making many gallon quantities spurred by an important laboratory
result. Here it should also be stated that even though direct fluorination can now
be done in an industrial scale, considerable skill is required in the laboratory on
prototype experiments directed toward preparation of new and unusual molecules. In
fact it is still true that a new postdoctoral fellow, even well trained from another
fluorine laboratory or a laboratory skilled in vacuum technology, will experience a
five to six month period before being competitive on such reactions. Good graduate
students sometimes require even longer to develop the "art of direct fluorination".
It should perhaps be stated that there are significant direct fluorination
efforts underway as well at Du Pont, Monsanto, Air Products and Dow Chemical in the
United States as well as a number of starts in projects in Japan. We think that the
3M effort with our group will lead the way and as this generates competition, we will
need even more funding to compete and have impact in our academic laboratory as we
deserve to still be in our own game. It should also be stated that there has been
immediate Air Force impact in a number of areas. For example, Exfluor Research
Corporation has a new 750 OF nonflammable hydraulic fluid on which initial testing at
Wright-Patterson was so successful that 20 gallons were ordered from Exfluor recently
for full-scale pump tests. 3M's new fluids will have impact on the military sectors
as well as the microelectronics industry and many other areas of endeavor.
Another area where our research on perfluoropolyethers will have major impact is
in the new Air Force Materials Laboratory initiative to make high temperature-high
performance perfluoropolyether lubricants for advanced jet engines. Both 3M and
9
Exfluor stand to make major contributions based on chemistry arising originally from
this AFOSR research program.
Our academic laboratory has been extraordinarily productive and successful under
research grant AFOSR-88-0084 over the last four years. On pages 18-20 we list on
contributions to the literature and it should be noted that we have 27 mainstream
direct fluorination publications coupled with 11 publications in the trifluoromethyl
organometallic area which we have also supported with our AFOSR funding bringing a
total of 38 publications. We have many projects that are just turning the corner
such as projects on new perfluorinated spiro compounds and new types of
organometallic compounds as well as other totally new directions for the next three
years. It should be noted that after intending to do so for a long time, we have
finally launched a project into selective fluorination for this go around and have
very promising results using lithium compounds, magnesium compounds, and boron
compounds for precursors at low temperatures. This is a very different direction in
our program.
10
HIGHLIGHTS FROM OUR DIRECT FLUORINATION PROGRAM
We have made many new perfluoropolyethers6 (Macromolecules 1985, 18, 1383):
hexafluoroacetone/ethylene oxide copolymer
CF 3 CF3
(-COCH 2CH2O-), - (-COCF 2CF20-), (I)I ICF 3 CF 3
hexafluoroacetone/propylene oxide copolymer
F3 C CH3 F3C CF 3
(-COCCH20-), -b/& ('COCCF 20-} (2)
F3 C H F3C F
hexafluoroacetone/oxetane copolymer
CF3 CF3
(-COCH2 CH 2 CH 2 O-), .- (-CCF2 CF2CF 2 0-), (3)
CF3 CF3
We have developed a new method involving esters and SF4 for fluorination of
perfluoropolyesters and converting them using a second SF4 step to obtain new
perfluoropolyethers7 (J. Am. Chem. Soc. 1985, 107, 1197):
General Synthetic Scheme
1111 ~ 00 1II I ,, II II(1)+OR ORf.-Z;-OCRtCOR'e+.
0 0 F F
liii1 SFS:V"r(2) + OCRCOR;+, - I RC0r#.
F F
F F F F
I I II(3) -*OCRqCO; + C OCR~COR;J
F F F F
a* I at
We have subsequently developed a method which is in press in J. Polym. Sci., Polym.
Chem. Ed. to make functional perfluoropolyether oligomers, diacids, diesters and
surfactants and starting materials for polymers using the same technology but using
less than stoichiometric amounts of SF4 .8
0 0
11
molecular wight
Fire 1. Gaumman di tributim of difuectnai perfluoropoay er P-
mla wighsu producad with mand x/2 wol of SF. Both sample arehbydlyd to produce the diad afiar ulmama with SF..
SPECTRAL ASSIGW'ENTS OF COMPOUNDS FROM 0 SF4 REACTION
Highest a/e 19 F NR 1 H NMRCompound in mass spec (rel. CFIC13) (rel. TS)
(CF2C02CH3 )2 159 -120.6 63.91P-C0 2 CH3
(C02 043 )2 59 63.89P-CO2 CH3
(CF2CO2H)2 145 -120.3 all.43P-CO2H
(C02H)2 45 69.00P-CO2H
SPECTRAL ASSIGNMENTS OF COMPOUWOS FROM 25% SF4 REACTION
Highest ro1e iComoun In mass spec F IM. N M
(CF2 C02€43 )2 159 -120.6 63.96-P-C020C3
(C0 2 013 )2 59 63.96*P-CO2 C43
H3CO2CCF2OCF2 CF2 CF2 CO2c43 275 a -77.8 63.96*a b c d 0 2 3 b 3.7
c -126.8
d -119.1
*Average chemical shift of CH3.s
12
SPECTRAL ASSIGNMENTS OF COMPOUNDS FROM SO% SF4 REACTION
Highest m/e 19 1
Compound in mass spec F NMR H NMR
H3 C02 CCF2 OCF CF2 CF CO 04 275 a -77.3 63.93"Z 2 P-CO2 CH3
a b c d b -84.2
c -127.0
d -119.0
H3C02CCF CF2 CF O(CF2 ) OCF2 CF2 CF C.CH3 491 a -119.0 63.93'P-C02 C43a b c d c b a b -127.0
c -84.2
d -88.7
H3 COCCF OCFCF 2CF 2CF CF2 COOI3 391 a -77.3 63.93'a 2b2 c 2c 2b 2a 223P-CO
2 CH3 b -84.2
c -125.5
H3CO CCF 2OCF CF CF CF OCF CF OCF 2CF CF2 CC0 3 607 a -77.3 63.93'2a bccb dd 2b2
-84.2
c -125.5
d -88.7
e -127.0
f -119.0
*Averaqe chemical shift of 043 's
SPIECTRAL ASSIGWMENTS OF COHPJKXDS FROM 100% SF4 REACTION
Highest m/e 19 1
Compound in mass spec F 1W NMR
(H3 CO2 CCF 2OcF2CF2CF2 CF2 C 2 ) 2 723 a -78.0 43.94*
a b c c b d b 483.3
c -125.3
d -18.6
(H3 CO2CCF2 CF2 CF2 OCF2 CF2 OCF 2 CF2 ) 2 823 a -119.3 63.94*
aPbc dd ce 2 CH3 b -126.6
c -83.3
d -88.6
e -12S.3
H3 CO2CCF2 O(CF 2CF2 CF2 CF2OCF 2 CF2 0) 2 CF2 CF2 CF2 CO2 CH3 a -78.0 63.940
a b C C b d d b f f b -43.3
c -125.3939p.COCH3 -88.6
* -126.6
f -119.3
*Average chemical shift of CH3'S
13
We have published a joint manuscript with Bill Jones of the Tribology Section of
the National Aeronautics and Space Administration, Lewis Research Center entitled,
"The Preparation of New Perfluoro Ether Fluids Exhibiting Excellent Thermal-Oxidative
Stabilities"9 (I&EC Research 1988, 27, 1497).
ThermaJ-Oxidative Investigation ofViscosity Data Perfluoroalkyl Ethers
kinematic viscosity, amt used, dec. dec. aftercSt compd" mg prod., mg 48 h, %
38 *C 54 OC ASTM perfluorotetraglyme 163 0.4 0.24compd (100 OF) (130 OF) slope HFPO hezarner 188 0.4 0.22
perfluorodiglyme 0.345 0.287 1.08 perfluoro(1.3-diethozypropane) 168 0.7 0.42perfluorotetraglyme 0.802 0.631 1.01 perfluoro(1,4-diethozybutane) 234 1.1 0.48perfluoro(l,3-diethoxypropane) 0.445 0.344 1.43 perfluoro(1,3-diethoxy-2,2-di- 221 1.Q 0.86perfluoro(1,4-diethoxybutane) 0.610 0.440 1.61 methylpropane)HFPO hexsmer 2.65 1.84 0.96 perfluoro(penta- 195 2.5 1.28perfluoro(1.3-diethoxy-2,2.di. 0.707 0.557 1.04 e-ythrityltetramethyl ether)
methyipropae) a100 Torr of 02 (- 25 *C) in each tube; test temperature, 360perfluoro(penta- 0.711 0.54 1.16 *C; test duration. 48 h.
erythrityltetramethyl ether)
Another major breakthrough was the synthesis of the first perfluoro crown
ethers10 1 1 (J. Chem. Soc., Chem. Commun., 1985, 1350; J. Am. Chem. Soc., in press):
FZ F2 properties and chamriztton of perfloo 1 :cron-5 and0 0 0 0 peffluoro 12-crown-4., Satisfactory elemental analyses (C. F) were
He I IF2 F2 OF2 obtained.
0 O ls-crowtt-5 12-cow-4
Boiling point."C 146 11812-erown-4 F2 F2
P.rflu.or 1-twn-4 I.r.(vapourphse).a -' 12.S0(s). 1260(vs).1228(vs). 188(vs).1158(vs). 1160(vs).
745(m) 1090m).F2 FZ 825(m).745(br)
SeIFZ N.m.r. (neat liquid) "9F -91.8(s) p.p.m. "F -90.0(s) p.p.m.-70 -45OC F2\(cit. CFCI.,) (ext. CTC3))
0F O F 1C 6 114.9 (s) 1Cb 114.9(s)
IS-crown-S F1 F2 Mass spectrum. 'z S80 (CtF 1 O,. M-) 445(C*FO 4.M--F)
perfluoro 15-crown-S s A table for the straight-chain fragmentation products listing mass
spectral and 19F data (two pages) is available from the authors.
F2 F2
0 0 F2 0 0 F2
F2 F 2
18-crown-6 F2 F2
perftuoro IS-crown-6
14
Additionally we have in press in the J. Org. Chem. a manuscript describing the first
perfluorocryptand [222]. 12
/CF 2 CF2 -CF
CF2 0 0CF 2
(C:F2 -CF2\ Cr-2 -CF 2 -CF 2 \N 0 0 /
0 0 CFCF2 CF2 -CF2 ' CF2 2
As will be later described, we have many other perfluoro macrocycle structures in
mind. Dr. Hsu-Nan Huang, during his stay in graduate school, produced
extraordinarily interesting new cyclic perfluorocarbons and highly branched
perfluorocarbons with unusual properties13 (Bull. Soc. Chim. Fr. 1986, 6, 993).
r
0
-4W .--4 . " or
0 or
F F
.. 601c blp. 152C m..-- n,-, . :o ,~~~.p. -OVCl.,,I"
P P
• -02T . -"
or.fur
F
Okp. 2010C bp 156*C low - j ZW .,. (1".21i
ULP. Yc InP. +130 C
I to 3e lm a,.
Wee
15
042 C~ft
0CFZFF2Ab I
C,!+ CH. I'll
CH4 3 -W T C F3 a I/ CF3 A C 3c cF3 C_
C,
-ee -2- as, 701
Org.Cem.195,50,516)
hart . 04 40% ment
C IF3CF2
I 1
5 C -CF2£72.2
CFC3 2 CF3CF3
1 J , a1, . 1 L0
2W I.
We have also had a strong component of our program directed toward new
perfiuCroethersof the small molecule variety 8 (J. Org. Chem. 1988, 53, 78; J.
Org. Chem. 1985, 50, 5156).
ChartI. 1C{'F Assignments'
ba$(Perfluorolsowoyll other
CF3 CF3I I a 118.049
F-C-O-,-cF b 102 962'I ICF3 CFs
bis(pert luoroosobutyl) etherCF3 CF3
41 C I a 118960F-C-CF2 -0-CF 2 -C-F b 88 980
I I c 117 659
CF3 CF3bin(perfluorosopentyl) oether
CF3 C @3( 119 2851I t d I b 90215
F-C-CF2 -CF 2 - O-CF2 -CF 2- c-F c 116.684*I I d 110 831
C173 %-P3
bis(porluroleopeffltyl Otter
CF3 CF31 I 1 a119 805
F3 C-C-CF2 -0-CF 2 -C-CF3 b 65 112I ~C 118, 895
CF3 tF3
In ppm relative to external Me4Si.
16
CCH,3 3 COCH 3 -120 *C -AT tCF 3 )3 COCF 3 + CF 3 )2 CFCF 2OCF 3 + (CF 3 )3CF + (CF,),CFCF2 H
feert -utyl methyl other oerhijoro~ferf- oerfluoro(iSaoutyl pertluoto[2- 7hmydromona-z-:yl methyl methyl ether) methylorocane) fluoro-2-
et he') methylorooane
H 3 F CF 3 F CF 3
-120 -C -AT FU§0 F. I C'o
H CH 3 F CF 3 F CF 3
2.2. 5. 5 -tetramethyl tershydroturan per tluoo (2.2. 5. 5- oer fluoro (2. 2. 5tet ramethylItetra hydrofuraft) t r imethyl toeIra hydrof ura n)
CF 3FCF
3 F
F CF3 + CF3 7J ~F
3- hydropentadecef Iuoro-2. 2.5.5-tetramethyltetrahydrofuran perfluoro( 2.2. 5-trimethyl tetrahydropyran)
CH 3 CH 3 CF 3 CF 3 CF 3 CF 31 F2IH@ I /\
CH 3 -C-O-CH 3 -CH -120 -C-T- CF 3 -C--O-CF 2 -CF + CFCF 2 -O-CF 2 CF
C"13 CH 3 Cfr 3 CF 3 CF 3 CF 3
fort-butyI iSObutyl ether perftuoro(fert-butyl 13obutyl ether) bis(aerfluoroosobutyt) other
CH 3 CH 3 CF3 CF CF 3 CF3
CH-O-CH CF-O-CF + CF-O-CFC 2 C 3 + C- CF F 3120OC - PT /C2C / / -C2
CH 3 CH 3 CF 3 CF3 CF 3 CF 3
isopropyl other bis~prfluoroisoropyI) other oert luorof .sopropyl per tiuoro(othylpropyl other) isopropyl other)
CH 3 0 .o.CH 3 C F3 0 CF 3
H m -120 -C - ATFFH2 H2 2 2
2.5-dimethyttetrahydroturan p*rfluoro(2.5-dimethyl tetrahydropyran)
0 20* - AT - F2 NCF 3+ CF3 CCF 2 )3CF 3 + CF 3(CF 2 )4 c~
F2 F2 peirfluoropentarm
7-oxabicyclo(2.2.1J hetotne oert Iuoro(2- perfiuorohexanoylethyltetrahydroturan) fluoride
CH 3 "H CF 3 F F
CH3 7 2 N CH3CHF 3 F3--- FF-1 11-25 CNF
HCFCH3 H CF3 3F
1. 2.2.6.6-pentamethyloipridene oertluorof 1.2. 2.6.6-penamethyipperdine)
CHIP CHIR CF 3 CF3I I 1F1C 3 -%-O- -CH 2 -O-C-CH 3 %' -N F-C-0-CF -CF 2 -0- CF
I I I IW73 CH 3 %CF3 CFr3
1.2-do-fef-butoxyethane perfluaro(1.2-d,-tery-butoxyethae)
CH 3C CF 3 F
CH 23-C-CH 2 -0- S -40-60 IC 0C Fo F
I F3'4 CF2%,H3 CIF 4F F
neopofityl I honyl ether pert Iuoro(cyclohoxyl neopontyl other)
Direct fluorination of perfluorocarbon ethers and amines.
17
We have a manuscript in press in J. Polym. Sci., Polym. Lett. Ed. on the synthesis of
SF5 substituted polymers II and 11.16
"JR.
(CH 2CH) -. (CH 2CH2).I I
SCOBu' SFII0
(CH 2 CH2 ). -~(CF2CF 2).I I
Another significant breakthrough that has been made in our laboratory is the
process for partial fluorination of gas separation membranes. We have known from
previous work that fluorination of polymer surfaces provides excellent gas diffusion
barriers and liquid diffusion barriers. We reasoned that light fluorination of a
selective gas separation membrane would change the selectivity in very pronounced
ways. We have then tested this hypothesis on normal thin film membranes and soon
hope to work on porous fiber (asymmetric) membranes. We have found that the
selectivity increases especially for "size separation" systems are very large indeed
(often after light fluorination the increase in selectivity is on the order of 103!).
These observations according to Professor Don Paul, a recognized authority in the
field, constitute a major breakthrough in separation technology. This area of
chemistry will also be a substantial part of our new program; it is now being
developed jointly with Professor Donald Paul of the University of Texas Department of
Chemical Engineering. The first joint paper on this phenomenon was published in
1986.17 We have presently three more manuscripts in press from this
collaboration.
18
Professor Richard J. Lagow
Recent Publications Arising from Air Force Office of Scientific Research
Grant AFOSR-88-0084
1. "The Synthesis of Perfluorinated Polyethers Via Polyesters Deriving FromHydrocarbons. A General Method," Makromol. Chem., Rapid Commun., 6, 85(1985) (with D.F. Persico and G.E. Gerhardt).
2. "The Synthesis of Perfluoropolyethers Via Hydrocarbon Polyesters: A NewGeneral Method," J. Am. Chem. Soc., 107, 1197 (1985) (with D.F. Persico andG.E. Gerhardt).
3. "Synthesis of Branched Perfluoroethers By Direct Fluorination; CopolymersBased on Hexafluoroacetone," Macromolecules, 18, 1383 (1985) (with D.F.Persico).
4. "The First Perfluoro Crown Ethers," J. Chem. Soc., Chem. Commun., 19, 1350(1985) (with W.H. Lin and W.I. Bailey, Jr.).
5. "Synthesis of New Cadmium Alkyls by Cocondensation of Cadmium Vapor withTrifluorosilyl and Trifluoromethyl Radicals," J. Chem. Soc., Chem. Commun.,1550 (1985) (with M.A. Guerra and T.R. Bierschenk).
6. "A General Synthesis for Symmetrical Highly Branched Perfluoroethers; A NewClass of Oxygen Carriers," J. Org. Chem., 50, 5156 (1985) (with D.F.Persico, H.N. Huang and L.C. Clark, Jr.).
7. "The Generality of Metal Atom-Free Radical Reactions and Synthesis of NewTrifluoromethyl Alkyls of Gold III and Silver," J. Organomet. Chem., 307, C58(1986) (with M.A. Guerra and T.R. Bierschenk).
8. "Group IIB Metal Alkyls: The Synthesis and Stabilization of Trifluorosilyland Trifluoromethyl Alkyls of Cadmium and Zinc," J. Am. Chem. Soc., 108, 4103(1986) (with M.A. Guerra and T.R. Bierschenk).
9. "Gas Transport in Partially Fluorinating Low Density Polyethylene," J. Appl.Polym. Sci., 31, 2617 (1986) (with C.L. Kiplinger, D.F. Persico and D.R.Paul).
10. "Bis(trifluorosilyl)mercury, Bis(trifluoromethyl)mercury and Bis(trifluoro-methyl)tris(trimethylphosphine)nickel," Organometallic Syntheses, 3, 426(1986) (with T.R. Bierschenk and W.I. Bailey, Jr.).
11. "High Yield Reactions of Elemental Fluorine," J. Fluorine Chem., 33, 321(1986).
12. "Synthesis of New High Molecular Weight Cyclic Fluorocarbons and HighlyBranched Fluorocarbons Such as Perfluoro-3,3-Diethylpentane," Bull. Soc.Chim. Fr., 6, 993 (1986) (with H.N. Huang).
19
13. "Further Developments of the Metal Vapor/Alkyl Radical Reaction. Synthesisof Tris(trifluoromethyl)indium and Bis(trifluorosilyl)cobalt and Their BaseAdducts," Revue de Chimie Minerale, 23, 701 (1986) (with M.A. Guerra andT.R. Bierschenk).
14. "The Synthesis and X-ray Crystal Structures of [Au(CH 2)2PPh 2]2(CF3 )2,[Au(CH 2)2PPh 2(C6 F5 )2 and [PPN][Au(C6 Fs),]: Two Dinuclear Gold(II) YlideComplexes Containing Alkyl and Aryl Ligands and the First Example of aHomoleptic Au(III) Pentafluorophenyl Complex," Inorg. Chem., 26, 357(1987) (with H.H. Murray, J.P. Fackler, Jr., L.C. Porter, D.A. Briggs andM.A. Guerra).
15. "Synthesis of Trifluorosilyl Organometallic Complexes From TrifluorosilylRadicals and Metal Atoms," J. Am. Chem. Soc., 109, 4855 (1987) (with T.R.Bierschenk, M.A. Guerra, T.J. Juhlke and S.B. Larson).
16. "Synthesis of Unusual Perfluorocarbon Ethers and Amines Containing BulkyFluorocarbon Groups; New Biomedical Materials," J. Org. Chem., 53, 78 (1988)(with H.N. Huang, D.F. Persico and L.C. Clark, Jr.).
17. "Synthesis of Perfluoro Crown Ethers: A New Class of Cyclic Fluorocarbons,"Pure Appl. Chem., 60, 473 (1988) (with W.H. Lin and W.I. Bailey, Jr.).
18. "The Preparation of New Perfluoro Ether Fluids Exhibiting Excellent ThermalOxidative Stabilities," Ind. Eng. Chem. Res., 27, 1497 (1988) (with W.R.Jones, Jr., T.R. Bierschenk, T.J. Juhlke and H. Kawa).
19. "Synthesis of the First Perfluoro Tetraalkyl Orthocarbonates," J. Org. Chem.,54, 1990 (1989) (with W.H. Lin and W.D. Clark).
20. "Synthesis of Bis(trifluoromethyl)xenon," J. Fluorine Chem., 45, 12 (1989)(with L.J. Turbini, R.E. Aikman and M.M. Brezinski).
21. "Synthesis of Tetrakis(trifluoromethyl)lead," Inorg. Chem., 28, 980 (1989)(with T.J. Juhlke and J.I. Glanz).
22. "A New Trifluorosilyl Exchange Reagent: Reactions of Cd(SiF ) .glyme withDibromo Metal Phosphine Complexes of Platinum, Palladium, and Nickel YieldTrifluorosilyl Substituted Dialkyl Compounds," J. Chem. Soc., Chem. Commun.,65 (1990) (with M.A. Guerra).
23. "A Synthesis for SF, Substituted Fluorocarbon Polymers," J. Polym. Sci.,Polym. Lett. Ed., 28, 297 (1990) (with H. Kawa, S.N. Partovi and B.J. Ziegler).
24. "Synthesis of Tris(trifluoromethyl)gallium and Its Adducts," J. Organomet.Chem., 390, C73 (1990) (with M.A. Guerra, D.W. Dyer and S.K. Mehrotra).
25. "The Synthesis of Perfluoro Highly Branched Heterocyclic Fluorine Compoundsby Direct Fluorination," J. Fluorine Chem., 50, 15 (1990) (with W.H. Lin).
26. "A New General Method for Preparation of Pentafluorosulfur-SubstitutedFluorocarbons: The Synthesis of Perfluoroneopentyl Sulfur PentafluorideUsing Elemental Fluorine as a Reagent," Chemistry of Materials, 2, 477 (1990)(with H.N. Huang).
20
27. "The Synthesis of the First Perfluoro Cryptand," J. Chem. Soc., Chem.Commun., 55, 5933 (1990) (with W.D. Clark).
28. "The Synthesis of Highly Fluorinated Alkylcyclohexanes for Use as OxygenCarriers; and the 19F and 13C NMR Spectra of Alkylcyclohexanes," J. FluorineChem., 50, 345 (1990) (with W.H. Lin).
29. "A Facile Synthesis for Functional Perfluoropolyether Oligomers, Diacids,Diesters and Surfactants," J. Polym. Sci., Polym. Chem. Ed., 29, 233 (1991) (withD.F. Persico).
30. "Novel Synthesis of Unusual Classes of Fluorocarbon Organosulfur CompoundsUsing Elemental Fluorine as a Reagent," Inorg. Chem., 30, 789 (1991) (withH.N. Huang and H.W. Roesky).
31. "The Direct Fluorination of Acetone", J. Fluorine Chem., 52, 37 (1991) (withW.D. Clark).
32. "Surface Fluorination of Composite Membranes Part I: Transport Properties,"J. Membrane Science, 55, 131 (1991) (with D.R. Paul, J.M. Mohr, and T.E. Mlsna).
33. "Surface Fluorination of Composite Membranes Part II: Characterization ofthe Fluorinated Layer," J. Membrane Science, 55, 149 (1991) (with D.R. Paul,J.M. Mohr, Y. Taru, and T.E. Mlsna).
34. "The Synthesis of Perfluorodicyclohexyl-18-crown-6 Ether", J. Chem. Soc.,Chem. Commun., 12 (1991) (with T.Y. Lin).
35. "Synthesis of Functional Perfluorinated Resins, Branched PerfluorinatedEthers and Perfluoroalkanoyl Fluorides," J. Chem. Soc., Perkin Trans. 1,871 (1991) (with H.N. Huang).
36. "XPS Characterization of Surface Fluorinated Poly(4-methyl-l-pentene),"J. Appl. Polym. Sci., 42, 2509 (1991) (with D.R. Paul, J.M. Mohr, Y. Taru, andT.E. Mlsna).
37. "A New Synthetic Procedure for the Preparation and Manufacture of Perfluoro-polyethers," Synthetic Fluorine Chemistry, G.A. Olah, R.D. Chambers and G.K.S.Prakash, Eds., Wiley Interscience, in press (with T.R. Bierschenk, T.J. Juhlkeand H. Kawa).
38. "Selective Formation of Molecular Oxygen/Perfluoro Crown Ether and PerfluoroCryptand Adduct Ions (Inclusion Complexes?) in the Gas Phase," J. Am. Chem.Soc., in press (with J. Brodbelt, S.D. Maleknia and T.Y. Lin).
39. "Selective Direct Monofluorination of Organolithium and OrganomagnesiumCompounds," J. Am. Chem. Soc., submitted (with J.P. DeYoung and H. Kawa).
40. "Synthesis of the First Perfluoro Crown Ethers," J. Am. Chem. Soc., inpress (with W.H. Lin, W.I. Bailey, Jr., S.B. Larson and S.H. Simonsen).
21
REFERENCES
1. G.E. Gerhardt and R.J. Lagow, J. Chem. Soc., Chem. Commun., 8, 259 (1977).
2. G.E. Gerhardt and R.J. Lagow, J. Org. Chem., 43, 4505 (1978).
3. G.E. Ge.-hardt, E.T. Dumitru and R.J. Lagow, J. Polym. Sci., Polym. Chem. Ed.,18, 157 (1979).
4. T.Y. Lin and R.J. Lagow, J. Chem. Soc., Chem. Commun., submitted.
5. J.L. Margrave and R.J. Lagow, Progress in Inorganic Chemistry, 26, 161 (1979).
6. D.F. Persico and R.J. Lagow, Macromolecules, 18, 1383 (1985).
7. D.F. Persico, G.E. Gerhardt and R.J. Lagow, J. Am. Chem. Soc., 107, 1197 (1985).
8. D.F. Persico and R.J. Lagow, J. Polym. Sci., Polym. Chem. Ed., in press.
9. W.R. Jones, Jr., T.R. Bierschenk, T.J. Juhlke, H. Kawa and R.J. Lagow, Ind. Eng.Chem. Res., 27, 1497 (1988).
10. W.H. Lin, W.I. Bailey, Jr. and R.J. Lagow, J. Chem. Soc., Chem. Commun., 1350(1985).
11. W.H. Lin, W.I. Bailey, Jr., S.B. Larson, S.H. Simonsen and R.J. Lagow, J. Am.Chem. Soc., in press.
12. W.D. Clark and R.J. Lagow, J. Chem. Soc., Chem. Commun., in press.
13. H.N. Huang and R.J. Lagow, lull. Soc. Chim. Fr., 6, 993 (1986).
14. H.N. Huang, D.F. Persico, L.C. Clark, Jr. and R.J. Lagow, J. Org. Chem., 53, 78(1988).
15. D.F. Persico, H.N. Huang, L.C. Clark, Jr. and R.J. Lagow, J. Org. Chem., 50,5156 (1985).
0
16. H. Kawa, S.N. Partovi, B.J. Ziegler and R.J. Lagow, J. Polym. Sci., Polym. Lett.Ed., in press.
17. C.L. Kiplinger, D.F. Persico, D.R. Paul and R.J. Lagow, J. Appl. Polym. Sci.,31p2617 (1986).
